Bleaching fats and oils



Patented Jan. 28, 1930 UNITED STATES PATENT OFFICE HORACE F. TAYLOR, I. SCHEBUBEL, AND GUY W. PHELPS, OI CHICAGO, ILLI- NOIS, ASSIGNORS TO SWIFT AND COMPANY, A CORPORATION 01 ILLINOIS BLEACHING rams AND ous them are pigments, such as carotin found in palm oil and butter, some belong to the unsystematic group known as lipoids, and some are resinous and other albuminous.

Various methods of bleaching oils and fats and removing these colored impurities have been proposed, some of them producing excellent results, but most of them being of limited application.

The method of the present invention is of more or less general application for bleaching oils and fats of the groups enumerated, and enables better results to be produced in many cases than with previously known methods. The invention is particularly advantageous for bleaching certain animal and vegetable oils and fats.

According to the method of the present invention, the oil or fat is subjected to the combined action of a bleaching earth and sulfuric acid, the earth and acid being added simultaneously or in immediate succession. The treatment of the oleaginous material with the earth and acid is advantageously effected at an elevated temperature, particularly where the material being bleached is solid or semisolid at ordinary temperature. Following the bleaching treatment, the oil and sludge are separated, e. g., by settling or filtration, or by a combination of these two operations. The oil may in some cases be subjected to a neutralization treatment, either before or after the settling, or before the filtration. So also, where the oil is settled before filtration, the settled oil may be subjected to further treatment with a small amount of earth before filtration.

The invention includes certain novel steps of the process, as well as the complete process itself. The nature and advantages of the invention, and the novel features thereof, will 1924. Serial No. 709,274.

more particularly appear from the following more detailed description and from the acco'mpanying claims.

In carrying out the invention, the fat or oil to be treated or bleached is heated to a suitable temperature, is subjected to thorough agitation in a suitable apparatus, a bleaching ma terial such as fullers earth, and an acid such as sulfuric acid, in suitable amounts, are added thereto with continued agitation until the desired reduction in color is obtained, and the oil is then further treated, as by settling and filtration to free it from the sludge, etc.

The temperature to which the fat or oil is heated before the addition of the bleaching material and acid thereto can be varied, the

temperature usually ranging from about 130 to about 220 F., but other temperatures, particularly lower temperatures, may be used. The lower the temperature employed, the longer the period of treatment required.

The treatment can be carried out in different types of apparatus, such as a tank or other vessel, lead-lined or constructed of other acid-resisting material, and with a suitable agitator capable of keeping the oil and bleaching material and chemicals in complete admixture and thorough agitation. When the oil is to be heated in the treating apparatus, the apparatus is equipped with a suitable heating device which may be in the form of a jacket or a closed coil of acid-resisting materiali or both a jacket and heating coil can be use As suitable bleaching materials may be mentioned fullers earth, kaolin, bleaching clay, diatomaceous earth (kieselguhr), variwith different grades of fats, oils and greases, but ordinarily about2% to about 8% of 60 B. acid is required, while somewhat larger quantities of lower strength acid would be required.

The temperature at which the process is carried out, as well as th'eamount of bleaching material and acid, can be varied, and will vary with different oils and fats, and may be varied even with the same oil or fat. We consider it advisable in all cases before proceeding to carry out the process on a large scale, to treat a test sample of the oil or fat in the laboratory to determine the best procedure for obtaining the maximum effect and bleaching action. The optimum temperature, as well as the proper amount of the bleachin material and the optimum strength an amount of the acid can readily be determined by simple preliminary tests, and these conditions and amounts can then be employed in large scale operations. It will be evident however that conditions which depart somewhat from the optimum conditions can be used and that certain of the conditions or factors of the process are more or less interdependent, the process requiring, for example,

a longer time at a lower temperature.

When the fat or oil has been heated to the proper temperature, and has had the bleach mg material and acid added thereto, the immediate and visible effect of the acid is to produce an apparent darkening of the fat or oil, but this is more apparent than real because after a moderate agitation, if a sample is removed and filtered, the color is found to be much lighter. The apparent darkening of the oil or fat is apparently due to flocculation of colloidal particles which are then readily absorbed by the bleaching earth. The coloring matters are absorbed by the bleaching earth more readily and in greater quantity, when the earth treatment is combined with an acid treatment in the manner above described, than when the earth is used alone. Most of the acid is also finally absorbed, so that, at the end of the treating rocess, the oil remains practically acid-free. en fullers earth or similar clay is the bleachin earth used, it is evident that a portion of t e sulfuric acid may react chemically with components or elements of the clay, so that only a small residue of the ori inal acid used may remain in or on the earth.

After the bleaching earth and acid are added, the thorough and rapid agitation is continued for a suitable len th of time, usually from one-half hour to our hours. The lower the temperature employed, the longer the period of agitation required. The progress of the bleaching action can be followed by taking samples periodically, during the agitation, and testing these samples for reduction of color, by removing them from the agitator tank, filtering them through filter aper, on which it is advisable to use a little iesel hr or other mechanical filtration medium, 1n order to ascertain the maximum color reduction, which can be determined by comparison with standard sam les by colorimetric readings-or any well-l nown laboratory method.

When the desired reduction in color is obtained, the a itation is discontinued and the contents of t e tank are allowed to settle for a sufiicient len h of time, for example, over night, althoug in man cases from one to two hours is suflicient. echanical methods of separation, such'as the use of centrifugal machines, may also be employed. In the or dinary process of settling by standing,.the oily mass se arates into two distinct layers, consisting o more or less clear bleached oil or fat and a bottom layer of earthy sludge, which contains ractically all of the acid added, absorbed ll with a certain proportion of fat or oil entangled therewith. I

After separation, for example by settling or centrifuging, the oily la er is removed to a se arate tank, and, if wel settled and relative clear, is filtered. The filtering of this oily a er can be facilitated and improved by the a dition of a small amount of fullers earth, diatomaceous earth or analo ous filtering material, to the oil and then filtering it through an ordinary filter press.

If the oilylayer is im erfectly settled it is either filtered as a who e or heated wit a small amount of a neutralizin agent, such as finely divided calcium car nate (powdered limestone, marble, chalk, etc.) or other neutralizing substance. The amount of neutralizing agent added may advantageously be just suflicient or slightly in excess of that required in order to remove anytrace of acid still remaining in the oil or fat or on particles of bleaching earth which have not settled; and this neutralizing treatment is then followed by further treatment and agitation with a small amount, e. g., about one-half of one per cent, to about three per cent, of filtering material, such as fuller s earth, diatomaceous earth (kieselguhr) or other analogous filtering material, and the entire mass is then filtered through a suitable filter press.

We find it advantageous in the process of the resent invention, for obtaining the best resu ts and the brightest and clearest fat or oil, to coat the cloth or septa of the filter press with a thin film or layer of diatomaceous earth (kieselguhr) or other similar filtering material. It is not usually necessary to use a specially designed or acid-proof press for the filtering operation, since the amount of acid left in the oil after the treatment, and particularly where the oily layer is treated a neutralizing agent, is usually neglig1 e.

The oil or fat should be maintained at y the bleaching earth, and

an elevated temperature, for example, around 150 F. during the filtration, al-

7 though this temperature is capable of some oil may be filtered directly through an acid resisting filter press. Instead of filtering this acid sludge directly in this way, it may be first treated with a neutralizing agent of the character mentioned above, for example, powdered calcium carbonate (such as finely ground limestone, marble, chalk, etc.) and then subjected to filtration. The metal filter cloth or septa may be advantageously coated with a layer of diatomaceous earth or analogous filtering material before filtration. In case the fatty or oily material resulting from this filtration contains water or water and acid, it is allowed to settle, the acid-water or water is withdrawn, and the remaining fat treated with about one-half of one per cent to three per cent of diatomaceous earth or bleaching earth, agitated and then filtered at a temperature of about 150 F. through a filter press whose cloth has been previously coated with diatomaceous earth as outlined above.

Instead of first separating the sludge from the fat or oil under treatment, by settling or centrifuging or otherwise, the entire mixt-ure of oil and fat with earth and acid may be pumped directly through a'suitable filter press. By proceeding in this way, the twostage handling of the treated material is avoided.

We have obtained best results with the process of the present invention by the addition of the bleaching earth first and the acid immediately afterwards, and we consider such procedure particularly advantageous and to be recommended. It is possible however to run the acid and earth into the oil or fat at the same time. The order of adding the bleaching materials and acids can also be reversed, by introducing the acid first and following this witlr the fullers earth addition, but in this case the bleaching action appears to be less satisfactory than when the earth is added first and followed by the addition of acid.

In' the case of certain fats and oils we find it advantageous to repeat the treatment a second time, using a much smaller quantity of acid in the second treatment than in the first. According to this method, after the oil or grease is heated to a suitable temperature in the -agitator tank, one-half of the calculated amount of bleaching earth and all the calculated amount of acid (as determined by small scale experiments) are added, and the mixture agitated in the usual way. The sludge is then settled out and the supernatant oil pumped oil. This oil is then.

treated with-the remaining half quantity of earth and 'a small amount of acid. After the usual agitation, the entire mass is then' filtered. While describing this variation of our process it is not our intention to describe all 0 the conceivable modifications through which our process might be run.

The invention will be further illustrated by the followinig specific examples, but it Will be understood that the invention is illustrated thereby, and is not limited thereto.

Ewample I .-Brown grease The brown grease is pumped in molten condition to an acid-proof agitator tank. The agitator is started and while the melted fat is 1n actlve motion, 6% of its weight of fullers earth is added. Immediately there'- after, or even before the last of the. fullers earth has been added, 2% of the weight of the oil, of 60 B. sulfuric acid is run in. Rapid and thorough agitation is continued for one and one-half hours, or until test samples removed from the agitator tank and filtered through filter paper show that maximum bleaching efiect has been obtained. The agitator is then stopped and the sludge allowed to settle over night while maintained in the molten state.

On the following morning, the supernatant oily liquid, which may contain in suspension a small quantit of colloidal particles, includ- The sludge remaining at the bottom of the original bleaching'tank is agitated, mixed with a suflicient quantity. of finely divided calcium carbonate to substantially neutralize the acid held in solution or suspension therein and pumped through an acid-proof filter press, the septa of which may be constructed of phosphor-bronze Wire screening or an equivalent acid-resisting metal, and which are coated with a small amount of diatomaceous earth.

The filtrate from the sludge may be combined with the principal product or used separately. The loss is about the same as in the ordinary process of bleaching by means of fullefis earth. A clear bright product is obtaine Example I I .'P1'ime tallo'w With the a 'tator in rapid motion, 4% by ing material and subjecting the same to filtraweight of fn ers earth and 4% by weight of tion. 40% sulfuric acid are added. The agitation In testimony whereof we aflix our signais continued vigorously for one hour, the tures.

5 agitator is sto ped and the product settle for HORACE F. TAYLOR two hours. e supernatant oil is filtered and ERWIN F. SCHERUBEL. the slud e treated and filtered separately as GUY W. PHELPS.

descri in the first exam 1e, or the entlre mixture may be filtered directly through a filter press after neutralizing by the addition of a suitable neutralizing agent, such as ground calcium carbonate.

Example [IL-Palm. oil

The palm oil is introduced into the agitator tank and heated to and maintained at a temperature of about 200 F. during the bleachmgl process. Seven per cent by weight of in ers earth and 10% lg weight of 34 sulm furic acid are added. apid and thorough 'tation is maintained for one-half hour, a r which the product is settled for two hours, whereupon the supernatant oil is filtered and the sludge neutralized and treated g as described in the recedin examples, or

the entire mixture is tered, after neutralization with finely divided calcium carbonate, through a press whose septa are coated with diatomaceous earth or equivalent filtering '0 medium.

It will thus be seen that the resent invention rovides an improved met 0d of bleach ing 011s and fats in which the oil and fat is treated while heated to a suitable temperature 85 with a bleaching material and acid which act conjointly upon the oil or fat, and that this action is continued with vigorous agitation of the mixture until the desired bleaching has been obtained. 40 It will further be seen that the treated oil can be separated from the earthy sludge by various methods ofprocedure which give a clear, bright oil product.

We claim: 46 1. The process of bleaching animal and vegetable oils and fats which comprises adding thereto a bleachin earth and sulfuric acid, the earth being a ded at least as soon in point of time as the acid so that the oils and fats are exposed to the action of the acid only in the presence of the earth, agitating the mixture, settling the sludge formed and filtering the supernatant oil through a layer of diatomaceous earth.

2. The process of bleaching animal and vegetable oils and fats which comprises adding thereto a bleaching earth and sulfuric acid, the earth being added at least as soon in point oftime as the acid so that the oils and fats are exposed to the action of the acid only in the presence of the earth, agitation the mixture permitting the sludge formed to settle from the treatedoil or fat, adding to 06 the treated oil or fat a small amount of filter- 

